The present invention relates to digital signing method, digital signing apparatus, portable information processing apparatus, digital signing system, and recording medium carrying a digital signing program and signature data creation program.
In recent years, methods and apparatuses are disclosed for providing digital signature to digital data, especially the data electronically digitalized by reading paper document by a scanner, or the like (Patent Reference 1, for example).
Patent Reference 1 uses an IC card for the device that carry out the encrypting processing used for creating digital signature data, wherein this reference allows plural persons to provide respective digital signatures on a single document by repeatedly using the same means, in other words, by using respective IC cards.
In Patent Reference 1, it is assumed thereby that each IC card carries the key for only one digital signature.
(Patent Reference 1) Japanese Laid Open Patent Application 2003-318885 official gazette